The invention relates to a scheme for timing information compensation of a clock signal, and more particularly to a clock system and a method for timing information compensation applied to a clock signal used in a mobile device such as a global navigation satellite system (GNSS) receiver.
Subsystems within a mobile product usually operate at different frequency bands, but, in order to save chip cost and area, several subsystems need to share one oscillator in the mobile product. Therefore, synthesizers are required to generate the particular frequencies for the subsystems according to the clock frequency from the oscillator. In general, the oscillator is temperature-compensated so that the clock frequency provided by the oscillator is precise. The power consumption of the temperature-compensated crystal oscillator is, however, greater than that of a conventional crystal oscillator.
For achieving power saving, a mobile product may change a clock frequency from a higher speed clock of a temperature compensated crystal oscillator to a lower speed clock of a conventional crystal oscillator during a specific time period. Since the conventional crystal oscillator has less resistance to the temperature change, the clock frequency of the conventional crystal oscillator is easily affected by temperature variation. Thus, the frequency/timing information carried by the clock signal of the mobile product during this specific time period is less precise. This causes performance decrease of the mobile product.